Exemplary embodiments relate to a nonvolatile memory device and a method of operating the same.
There is an increasing demand for nonvolatile memory devices which can be electrically programmed and erased without the refresh function of rewriting data at specific intervals.
The nonvolatile memory device can be electrically programmed and erased by shifting threshold voltages of memory cells where electrons within the memory cell, e.g., an oxide layer, are moved by an electric field applied to the oxide layer.
In order to perform a program operation or an erase operation for memory cells, a pulse of high voltage is applied to the gates of the memory cells several times. A potential difference occurs and charges move in the memory cells in response to the applying of the pulse, and thus the threshold voltages of the memory cells are shifted to store the corresponding data therein. With the development of relevant technology, progressively increasing number of memory cells are provided in the nonvolatile memory device. In order to obtain a desired threshold voltage distribution of the memory cells, high voltage is to be applied to the gates of the memory cells in various ways. Accordingly, the physical properties of the memory cells may deteriorate, and the operation time, the operating current, or the consumption of current may be increased.